This invention relates to a document handling system for copiers in which documents may be recirculated in a separated manner for pre-collation copying, or selectively individually copied.
For the faster xerographic and other document copiers now in commercial use, it is increasingly desirable to provide for automatic handling of the individual original documents being copied in order to utilize those higher speed copying capabilities. However, such documents can vary widely in sheet size, weight, thickness, material, condition, humidity, age, and value. The documents may have curls, wrinkles, tears, "dog-ears", cut-outs, overlays, paste-ups, tape, staples, adhesive areas, or other defects. Yet it is desirable to be able to automatically copy a set of documents with a mixture of sizes, types, and conditions. Further, it is desirable to automatically handle such documents with a relatively compact and inexpensive document handling system. Preferably the document handling system is one which may be placed over an existing or conventional external transparent copying platen (window) of a copier, and which can utilize the same existing or conventional optics system. That is, it is desirable that the automatic document handling system be readily removable from the platen area by the copier operator whenever desired to allow conventional manual copying of documents, such as books, on the same copying platen.
An especially difficult document handling problem is the automatic separation of individual documents for copying from a stack or set of unseparated documents without damage to or wear of the documents. Thus, a document handling system which handles pre-separated documents is desirable.
Another highly desirable feature for a document handling system for a copier is to provide automatic document recirculation for pre-collation copying. As discussed, for example, in detail in U.S. Pat. No. 3,963,346, issued June 15, 1976, to D. J. Stemmle, et al., at Columns 1-4, such pre-collation copying systems provide a number of important advantages. The copies exit the copier in pre-collated sets, and do not require subsequent sorting in a sorter or collator. On-line finishing and/or removal of completed copy sets may be provided while additional copy sets are being made from the same document set. Any desired number of such copy sets may be made by making a corresponding number of recirculations of the document set in collated order past a copying station and copying each document once each time it recirculates.
However, a disadvantage of pre-collation copying systems is this fact that the documents must all be repeatedly recirculated and repeatedly individually copied the number of times equivalent to the desired number of copy sets. Thus, for example, to make 10 copy sets of a 5 (page) document set or book, one copy at a time would be made of each of the 5 document pages in this order: Pages 1, 2, 3, 4, 5; 1, 2, 3, 4, 5, etc.; repeated a total of 10 times to make the desired 10 copy sets. For bi-directional pre-collation copying this document copying sequence would, instead, be 1, 2, 3, 4, 5; 5, 4, 3, 2, 1; 1, 2, 3, 4, 5; etc.. Also, document recirculation normally requires an increased and non-linear document path length. Thus, it may be seen that increased document handling is necessitated for a pre-collation copying system as compared to a post-collation system in which all the desired copies are made at one time from each document page and collated subsequently. In such a post-collation copying system the document set need only be circulated once to fill the bins of the copy sheet sorter or collator with the number of copy sets desired (limited in number, however, to the number of bins).
The present invention provides an automatic precollation document handling system in which a set of individual documents may be maintained pre-separated for any desired number of recirculations, or alternatively and selectively the same document handling system may be used for non-recirculating document handling with a short and simple document handling path, to minimize document handling, and to maximize the ability to copy different or defective documents, and to make one or more copies of individual documents at the same time. The system disclosed herein is particularly suitable for, and compatible with, conventional copier platens and optics systems. It is suitable for use as a removable or auxiliary document handling system, removably overlying an existing or conventional copier platen to selectively allow use of that same platen and its associated optics for manual or other non-pre-collation copying.